The present invention relates to compositions and methods for treating tinnitus. Tinnitus can be described as "ringing" and other head noises that are perceived in the absence of any external noise source. It is estimated that 1 out of every 5 people experience some degree of tinnitus.
Tinnitus can be classified into two forms: objective and subjective. Objective tinnitus, the rarer form, consists of head noises audible to other people in addition to the sufferer. The noises are usually caused by vascular anomalies, repetitive muscle contractions, or inner ear structural defects. The sounds are heard by the sufferer and are generally external to the auditory system. This form of tinnitus means that an examiner can hear the sound heard by the sufferer by using a stethoscope. Benign causes, such as noise from TMJ, openings of the eustachian tubes, or repetitive muscle contractions may be the cause of objective tinnitus. The sufferer might hear the pulsatile flow of the carotid artery or the continuous hum of normal venous outflow through the jugular vein when in a quiet setting. It can also be an early sign of increased intra cranial pressure and is often overshadowed by other neurologic abnormalities. The sounds may arise from a turbulent flow through compressed venous structures at the base of the brain.
Subjective tinnitus may occur anywhere in the auditory system and is much less understood, with the causes being many and open to debate. Anything from the ear canal to the brain may be involved. The sounds can range from a metallic ringing, buzzing, blowing, roaring, or sometimes similar to a clanging, popping, or nonrhythmic beating. It can be accompanied by audiometric evidence of deafness which occurs in association with both conductive and sensorineural hearing loss. Other conditions and syndromes which may have tinnitus in conjunction with the condition or syndrome, are otosclerosis, Menier's syndrome, and cochlear or auditory nerve lesions. Hearing loss, hyperacusis, recruitment, FMS, and balance problems may or may not be present in conjunction with tinnitus.
Many sufferers report that their tinnitus sounds like the high-pitched background emitted by some computer monitors or television sets. Others report noises like hissing steam, running water, chirping crickets, bells, breaking glass, or even chainsaws. Some report that their tinnitus temporarily spikes in volume with sudden head motions during aerobic exercise, or with each footfall while jogging. Objective tinnitus sufferers may hear a rhythmic rushing noise caused by their own pulse. This form is known as pulsatile tinnitus.
The cause of tinnitus is largely unknown. Various conditions have been identified which are associated with it, including, allergy, diseases, such as Lyme disease, growths/tumors, general health impairments, injuries, noise exposure, syndromes, such as temporo-mandibular joint (TMJ) syndrome, and medication side-effects.
The most important treatment for tinnitus is avoidance of exposure to excessive noise, ototoxic agents, and other factors that may cause cochlear damage. Masking the tinnitus with music or through amplification of normal sounds with a hearing aid may also bring some relief. Although intravenous treatment with antiarrhythmic drugs (e.g., lidocaine) suppresses tinnitus in some individuals, evidence suggests no benefit with oral agents that are potentially suitable for long-term symptom relief. In addition, systemic procaine has been suggested. See U.S. Pat. No. 5,064,858. Among the numerous drugs that have been tried, oral antidepressants (e.g., nortriptyline at an initial dosage of 50 mg orally at bedtime) appears to be most efficacious. Thus, there remains a need for compositions and treatments for tinnitus.